This invention is concerned with dynamoelectric machines and more particularly with commutator type generators for supplying speed responsive direct current. Specifically, the invention relates to a direct current generator having a shell rotor displaced relative to permanent magnet pole pairs. More particularly, the invention is concerned with a direct current generator including a cylindrically shaped shell rotor having a multiplicity of longitudinally aligned copper segments in which said segments current is induced when the segments are displaced relative to permanent magnet pole pairs.
Direct current generators have conventionally embodied a rotor comprised of coil windings in which currents are induced by a relative displacement of the windings with respect to a magnetic field. These coils are conventionally wound around a thin cylindrical nonmagnetic member to form a rotor as is typically shown in Hayes, U.S. Pat. No. 2,860,267. Alternately, direct current generator rotors have been constructed of a tubular nonmagnetic material supporting a plurality of windings of the printed circuit type which are deposited on the tublar nonmagnetic material.
Both of these prior art rotor constructions present several obvious problems. In the case of the coil-wound rotor, the cross sectional area is limited by two factors. The first factor is that for a given pole pair gap, the size of the coil conductor cross-sectional area is limited by the necessity of having a nonconducting supporting material. The second factor reducing cross sectional area is the configuration of the coils. That is, coils having a circular cross section do not yield the most efficient utilization of space within the magnet pole pair gap. In the case of the printed circuit type of windings, the cross-sectional area of the conductors is limited not only by the necessity of having a non-conducting supporting material, but also by the inherent thinness of the printed circuit type of windings.
The present invention represents an improvement over the prior art in that maximum use is made of the magnet pole pair air gap, resulting in a direct current generator capable of generating large currents at high efficiencies.